There are many permanent magnet brushless polyphase electric motors such as those described in Patent EP0949747 or EP2002531, both by the Applicant. Motors of this type are composed of a wound stator assembly and a rotor assembly comprising a plurality of magnets. In order to ensure the electrical switching of the different phases of these motors, the generally chosen solution consists in using at least one Hall probe placed opposite the plurality of magnets or an auxiliary magnetized assembly dedicated to this switching. In order to embody an actuator, the Hall sensors, as well as the electronic circuit controlling them, and the electrical connector assembly of the motor phases must be assembled in an integral product which can be placed and used in any application (for example for moving different valves, flaps or shafts in an internal combustion engine).
There are various forms of embodiment in prior art solutions. For instance, some solutions consist in partially overmoulding the motor, most often only the stator is overmoulded. Patent Application PCT WO/2009/055625 relates to a stator assembly and to a method for producing a stator assembly. The stator assembly is overmoulded with a thermally conductive and electrically insulating polymer composition. The stator core of the stator assembly is coated with an adhesive component to allow better heat transfer to the interface of the stator core and the overmoulded coils.
Patent application EP1677404 also discloses a motor for an electric power steering, where the connection of the coil can be easily embodied while saving space, and a method of manufacturing the engine. Stator coils are assembled into a stator core and connected per phase by connecting rings. Patent applications EP2781758, US2010/301691, WO2011159674 or US2008/023028 describe other exemplary embodiment of prior art.
Prior art solutions have the disadvantage of a complicated assembly, requiring precise mechanical positioning of the stator parts in the housing and/or with respect to the rotor. During assembly, it is necessary to make multiple mechanical and electrical connections in order to ensure the connection of the coils to a wiring harness or connection elements with the electronic circuit, the electrical connectors and if necessary with a printed circuit. These different operations require high precision and cause fragility of the device.
The overmoulding solutions known in the prior art do make it hard to ensure the coating of all the components of a stator structure and only partially avoid the problem of assembly and electrical connections. Specifically, in the solution proposed in Patent Application EP1677404, the wound stator and the connector technology do not form an encapsulated assembly, which leads to mechanical weaknesses.